The Sun

1. The average density of the Sun is

a. near that of water (1.0 g/cm³)*

b. near that of Earth (5.5 g/cm³)

c. near that of lead (11.4 g/cm³)

d. ~ 140 g/cm³.

2. The interior of the Sun is a

a. gas*

b. liquid

c. solid.

3. The intensity of sunlight reaching the Earth is the

a. solar luminosity

b. solar constant*

c. solar-Boltzmann constant

d. solar flux.

4. If the temperature of the core of the Sun were less than the surface temperature the Sun would

a. blow-up

b. expand slowly

c. collapse*

d. stay the same as it is now.

5. The two most abundant elements in the Sun, with the most abundant given first, are

a. carbon, oxygen

b. iron, hydrogen

c. helium, nitrogen

d. nitrogen, helium

e. hydrogen, helium.*

6. Hydrostatic equilibrium is an equilibrium between

a. hydrogen and carbon

b. water, hydrogen, and oxygen

c. gravity and outward pressure*

d. water and electric (static) charge.

7. An isotope of hydrogen is

a. helium

b. deuterium*

c. lithium

d. a neutrino

e. a neutron.

8. High temperatures are required for hydrogen fusion reactions to occur because

a. high potential energy is required

b. like charges repel*

c. neutrinos can be explained only with high temperatures

d. opposite charges attract.

9. The solar atmosphere is

a. the photosphere

b. the chromosphere

c. the corona

d. all the above*

e. separate from all the above

10. What we see visually as the surface of the Sun is the

a. photosphere*

b. chromosphere

c. corona.

11. The temperature of the photosphere is roughly

a. 5,000 K*

b. 50,000 K

c. 100,000 K

d. 1,000,000 K

12. The chromosphere of the sun

a. is hotter than the photosphere. *

b. appears yellow-white in color during total solar eclipse.

c. is the visible surface of the sun.

d. produces an absorption spectrum.

e. all of the above.

13. The temperature of the solar corona is approximately

a. 5,000 K

b. 10,000 K

c. 50,000 K

d. 100,000 K

e. 1,000,000 K*

14. Differential rotation of the sun

a. causes the heating in the chromosphere and corona that makes them hotter than the photosphere.

b. is caused by the magnetic dynamo inside the sun.

c. implies that the equatorial regions of the sun rotate more rapidly than the polar regions. *

d. causes the sunspots to migrate slowly from the equator toward the poles as the sun rotates.

e. implies that the sun's southern hemisphere and northern hemisphere rotate in opposite directions.

15. Prominences are associated with

a. sunspots*

b. granulation

c. absorption lines

d. the interior

e. none of the above.

16. The solar wind is mostly associated with

a. sunspots

b. prominences

c. coronal holes*

d. Jupiter's magnetic field.

17. The sun's magnetic field is evident in the looped shapes of

a. solar flares.

b. sunspots.

c. the corona.

d. granules.

e. prominences. *

18. The Earth's magnetic field protects us from the solar wind. What does this tell you about whether or not the solar wind particles are charged?

a. Solar wind particles are not charged.

b. Solar wind particles are charged positively.

c. Solar wind particles are charged negatively.

d. Solar wind particles are charged either positively or negatively.*

e. None of the above.

19. Sunspots appear dark because they are

a. cooler than their surroundings*

b. hotter than their surroundings

c. formed on the photosphere

d. formed in the chromosphere.

20. Using the Zeeman effect, astronomers can measure the ______of the Sun.

a. rotation speed

b. chemical composition

c. magnetic field*

d. velocities of solar granulation

e. mass.

21. The most important clue to the origin of sunspots is their

a. appearance

b. lower temperature than the surroundings

c. position in the atmosphere

d. strong magnetic field.*

22. A complete period of the solar cycle takes

a. one year

b. 11 years

c. 22 years*

d. 33 years

e. 44 years

23. When at a solar eclipse is it safe to look at the sun?

a. It is safe to look at the sun with the naked eye only during totality, when the photosphere is completely hidden.*

b. It is safe to look at the sun with the naked eye after the diamond ring effect.

c. It is safe to look at the sun with the naked eye when the chromosphere is visible.

d. All of these.

e. None of these.

24. Why do x-ray photographs show the corona?

a. Because x-rays can pass through interplanetary space.

b. Because the corona does not emit anything but x-rays.

c. Because such hot gas emits strongly in x-rays, while the photosphere is too cool to emit x-rays.*

d. Because light from the chromosphere does not interfere with the x-rays of the corona.

e. None of these.

25. What is the relation of filaments and prominences?

a. Filaments come from the umbrae of sunspots and prominences come from the penumbrae.

b. Filaments are prominences seen in projection against the solar disk.*

c. Filaments follow magnetic field lines whereas prominences follow electric field lines.

d. Filaments follow electric field lines whereas prominences follow magnetic field lines.

e. None of these.

26. The distance to the Sun can be found by

a. timing the planet Mercury in its orbit

b. bouncing radar signals off the nearby planets *

c. observing the Sun and Moon during a total solar eclipse

d. using a very long meter stick

27. The Sun's mass can be found by

a. using Kepler's third law, if the Earth-Sun distance is known *

b. comparing the Sun to other nearby stars

c. comparing the Sun and Moon during a total solar eclipse

d. measuring the temperature of the solar material

28. In order to determine the Sun's luminosity, we must know

a. the size of the Sun

b. the size of the Earth

c. the distance from the Earth to the Sun*

d. the mass of the Sun

e. the amount of hydrogen in the Sun

29. The Sun's temperature can be determined if you find out

a. the wavelength at which the Sun's spectrum is brightest

b. the Sun's luminosity and radius

c. which elements are producing lines in the solar spectrum

d. all of the above *

e. none of the above

30. When solar abundances are determined from the Sun's absorption spectrum, to what region of the Sun do these abundances directly apply?

a. core

b. half-way out from center

c. photosphere *

d. chromosphere

e. corona

31. In fusion reactions, energy is liberated because

a. some mass is converted directly to energy *

b. the helium produced is more massive than the hydrogen that is fused together

c. fusion reactions occur near the Sun's surface

d. hydrogen is a very hot gas

32. The proton-proton chain

a. combines two hydrogen nuclei to produce a single helium nucleus and energy.

b. splits a helium nucleus to produce 4 hydrogen nuclei and energy.*

c. is the mechanism that increases the temperature between the photosphere and corona of the sun.

d. is the interactions between protons in Earth’s atmosphere that produces auroras.

e. produces energy in the core of the sun in the form of gamma-rays, positrons, and neutrinos. *

33. The two processes by which most energy is transferred from the Sun's core to the photosphere are

a. conduction and convection

b. radiation and convection *

c. radiation and conduction

d. radiation and neutrino emission

e. neutrino emission and convection

34. Solar granulation is an indication that

a. the Sun's corona is very hot

b. neutrinos are emitted by the Sun

c. energy is transported out of the Sun by convection *

d. sunspots are not solid

e. the Sun is a quiet star

35. The solar neutrino experiment shows that

a. more neutrinos were emitted by the Sun than expected

b. fewer neutrinos were emitted by the Sun than expected *

c. more neutrinos were emitted by the Sun than protons or electrons

d. neutrinos were being emitted by the Sun exactly as expected or predicted